Method and apparatus for pumping and heating oil wells



T. J. NOWAK April 13, 1954 METHOD AND APPARATUS FOR PUMPING AND HEATINGOIL WELLS Filed Oct. 25, 1950 Illu) l .Ii .l1 |11 'Ill/lll will PatentedApr. 13, 1954 METHOD AND APPARATUS FUR PUMPING AND HEATING OIL WELLSTheodore J. Nowak, San Pedro, Calif., assignor to Union Oil Company ofCalifornia, Los Angeles, Calif., a corporation of California ApplicationOctober 23, i956, Serial No. 191,575

This invention relates to a method and apparatus for heating oil wellswhereby the rate of oil now and the net yieldof oil can be increased.More particularly, this invention relates to a method and apparatus forthe combustion of busted within the welll bore. Such methods havegenerally met with Alittle` or no commercial suc,- cess partly due tothe type'of apparatus employed andV poor heat `transfer obtained therebyand partly due to the fact that the hot oil is rapidly cooled duringtransitfrom the oil-bearing formation to the earth surface with theresultant deposition of wax and other materials. The wax and otherdeposits cause rapid plugging, fouling' of the rods, pumps and otherelements.

A new method for heating wells has been discovered which combusts aminor portion of the oil by a submerged flame technique within the Wellbore in close proximity to `the oil-bearing formation. The combustiongases are employed to transfer heat to the surrounding oil and assist inthe pumping of the heated oil. The heated gases and oil are preferablyalso passed through a heat transfer zone, wherein a substantial portionof the heat generated' is transmitted'through I'.

radiation or convection to the surrounding oiloearing formation.

1t is an object oi this invention to heat an oilbearing formation andsimultaneously recover oil from the oil-bearing formation whereina minorportion oi the oil production is combusted and the heated products fromsuch combustion are passed through a heat transfer zone wherein a maiorpart of the heat generated thereby is transmitted to the oil-bearingformation.

It is another object of this invention to provide an apparatus forsimultaneously pumping an oilbearingr formation and heating suchoil-bearing 10 Claims. 4(Cl. 16B-17) formation, which apparatus employsa portion of v the oil flow as fuel therefor.

It is another object of this invention to decrease pumping costs in theproduction of waxy crude oil or other crudes which deposit gums orsolids upon cooling;

It is another object of this invention to utilize a portion'of the oilproduction within a well bore in order to heat the oil-bearing formationand pump orassist in pumping such oil production from the oil pool atthe bottom of the well.

It is another object of this invention to cornbust oil within an oilWell bore by a submerged combustion technique wherein a maximum transferof heat from the combustion zone to the surrounding oil is effected andwherein the heated oil resulting therefrom is employed `to heat theoil-bearing formation.

Other objects of this invention will become apparent to those skilled inthe art as the description thereof proceeds.

Briefly, this invention relates to a new method for heating oil-bearingformations 4and pumping the oil produced therefrom. The invention is inpart based on a new submerged burner. Oxygen or other molecularoxygen-containing gas, with or without'preheating, is passed fromy theburner into a combustion zone which is surrounded by crude oil. Aportion of the crude oil surrounding the combustion zone is drawn intocontact with the oxygen and is combusted as a result thereof. The heatgenerated in the combustion zone is radiated or otherwise transmitted tothe surrounding crude oil.

In a preferred modification of the invention the burner is located belowthe liquid level within the bore hole such that a continuous supply ofcrude oil may be drawn into contact with the combustion `zone and passedupwardly through a Venturi constriction and thence to the earthssurface. A plurality of heat radiating varies surrounds the Venturiconstriction to facilitate the transfer oi heat from the oil and gasescarried therein to the surrounding media. In another modication of theinvention a plurality of such burners may be employed in series withsuccessive burners taking suction on the eluent oil from the precedingburner and Venturi yconstriction combination. In another modication ofthe invention a portion of the hot crude oil, after passage through theVenturi constriction, may be discharged through a suitable opening intothe bore hole.

While the exact reasons for the increase of oil production upon heatingare not known, it is quite possibly due to the decreased viscosity ofthe oil in the heated formation, the melting of wax deposits in theformation, the expansion of gas pockets in the formation during heatingand the like.

Figure i shows `an elevation View` oi an oil well employing a pluralityof burners in order to heat crude oil and the surrounding formation andalso to provide energy for pumping the crude oil to the earth surface.

Figure 2 shows a partly sectional elevation View of the burner andVenturi constriction employed below the surface of the oil pool inFigure 1.

Figure 3 shows a cross-sectional view of Figure 2 taken through theplane 3 3.

Figure 4 shows a modification of the burner which is employed in Figure1 above the surface of the oil pool.

Figure 5 shows a sectional elevation View of an alternative type burnerwhich may be employed below the surface of an oil pool and wherein the-oxygen is supplied to the burner through a central coaxial pipe passingthrough the one or more Venturi constrictions and wherein part of or allof the heated oil may be recycled to the oil pool in contact with theformation.

Figure 6 shows a method for piping oxygencontaining gas through aplurality of burners by means of a central coaxial pipe.

Figure 7 shows a means for igniting a burner within the well bore.

Figure 8 shows a sectional elevation view of a conventional type pumpwhich may be employed at any suitable distance in the tubing above theburner-pump of this invention.

Perhaps the method and apparatus of this invention can best beunderstood by reference to the drawings.

Referring now more particularly to Figure 1, oil well I I is drilledfrom earth surface I2 through various formations I3 into oil-bearingformation It. Casing I5 is tted with casing head i5 and passesdownwardly through the well bore to within a short distance aboveoil-bearing formation i4. Casing I5 is fitted with a conventional gasoutlet system indicated by pipe I'I.

Tubing I8 is tted with oil production line I9. Tubing IS passesdownwardly through casing head I5 and through well I I to the bottomthereof. At the earths surface compressor takes suction on line 2Icarrying oxygen-containing gas and forces such gas under pressure intooxygen f supply line 22 which passes downwardly through casing head I5and into well I I.

The lower portion of tubing I8 is fitted with plug 23 for protection incase of fall. Above plug 23 is located burner housing 24 enclosingburner 25. Burner housing 24 is fitted with a series of ports 25 whichpermit the flow of oil from the external oil pool 2l' into contact withburner 25. Above burner housing 24 is located successively heat transferunit 28, burner housing 29, heat transfer unit 35, coupling 3i, burnerhousing 32, heat transfer unit 3s and lconnecting tubing 34 which passesto the earths surface.

Heat generated by burner 25 is at least partially radiated by heattransfer unit 28 to the surrounding oil pool 2l which in turn heats thesurrounding oil-bearing formation I4 by convection. The burner locatedwithin burner housing 29 and heatV transfer unit 3B are located abovethe liquid level of oil pool, 2l' and radiate heat from the het oi1fiowing therethrough to the surround- `ing oil-bearing formation I4through the intervening gaseous phase by means of radiation. The oilflow from the formation is increased as a result of the heatingregardless of the method of transfer. More effective heat transfer tothe formation is obtained by radiation through the gas phase, however.

At the earths surface electrical generator supplies a suitable currentto ignite the various burners. The one terminal -of generator 35 isconnected to insulated ignition rod 35 which passes downwardly throughtubing head 31 and tubing I8. The lower tip 36 of ignition rod 35 isnon-insulated and comprises an exposed electrically conductive surface.The other terminal of generator 35 is connected to tubing I8 throughcasing head I6 to which it is grounded. Ignition rod 35 is slideablethrough the several burner elements and when passed into the proximityof a burner can be momentarily charged by generating a current ingenerator 35 to produce a spark of electric arc in the vicinity of theburner in order to ignite the burner.

Referring now more particularly to Figure 2, which shows an enlargedcross-sectional portion of the burner and heat transfer unit assembly,air or other oxygen-containing gas is introduced through line 22 intoburner 25 whence it passes into the combustion zone surrounding burner25. Burner housing 24 is submerged in the oil pool 2'! and crude oilflows through the several ports 26 into contact with the combustion zonesurrounding burner 25. A portion of such oil in contact with thecombustion zone is continuously combusted in the ame to produceoxidation products which in turn transmit heat to the enveloping oil.The hot oil and gases flow upwardly through burner housing 24 and enterconverging zone inlet 4I) whence they pass through constriction zone 4Iand thence to diverging zone outlet 42. The inlet 4I) and outlet 42 ofheat transfer unit 28 are surrounded by a plurality of heat transfervanes 43 which transmit and radiate heat from the hot oil flowingwithin, through the chamber walls 44 to the surrounding media which maybe either liquid or gaseous. The partially cooled oil leaving outlet 42passes upwardly to a second burner housing 29 or other suitable couplingto thev well tubing.

While only a single burner and heat transfer unit of Figure-1 has beenshown in detail, the remaining burners, burner housings, and heattransfer units are of substantially the same ccnstruction as has beenshown in Figures 1 and 2 with the exception that plug 23 is replacedwith a suitable nipple or other coupling. Where the burner housing isnot located below the liquid level of the oil pool as in the case ofburner housing 29 and burner housing 32 of Figure 1, no ports areprovided for the inlet of oil. In certain cases small ports with orwithout attached ducts may be provided to discharge a portion of the hotoil from the tubing to the surrounding media in order to provide moreeiiicient heat transfer to the surrounding media. In all such cases,however, the combustion zone of each of the burners is of the submergedtype wherein a part of the oil or gas is burned beneath the oil surfaceso as to heat the oil simultaneously.

Referring more particularly to Figure 4, the oxygen containing gas maybe introduced through line 5I) to a plurality of burners 5I and 52,respectively, which are suitably displaced to permit the coaxial passageof oxygen-containing lines, burner rods for igniting burners and thelike. The burner housing 53 shown in Figure 4 has no ports for the entryof oil and may therefore be employed above the liquid level within wellbore in those cases where it is not desired to recycle hot oil.

Referring more particularly to Figure 3, which is a cross-section ofFigure 2 through the plane 3 3, the hot oil passes through the centercon- Striction 4I. The walls 44 of the outlet 42 and 7 nby convection orby conduction in the oaseV of recycle oil. Furthermore, the combustiongases are not wasted but are employed to assist in pumping the oil andin maintaining such oil in a continual state of turbulence during itstransport to the earth surface so as to minimize the normal depositionof wax which readily occurs under these circumstances.

Furthermore, this invention relates to a new type of subsurface burnerand heat transfer system for use in oil wells which accomplish heatingand pumping.

The method of use of the burners and heat transfer units of thisinvention depends primarily upon the desired result. Very often only asingle burner and a single heat transfer section need be employed,particularly when the oil is readily pumpable, with only slight heatingand when a conventional pump is to be employed in conjunction therewith.Where the production from the well is extremely low indications are thatthe well is very amenable to heat treatment and under these conditions aplurality of burners and heat transfer units are normally employed inproximity of the oil-bearing formation.

Where a plurality of units are employed, and

sometimes under other circumstances where but a single unit is employed,it is desirable that the heat transfer section be located above theliquid level of the oil pool and facing the exposed surface of theoil-bearing formation. Under these conditions there is obtained amaximum heat transfer from the heat transfer unit to the formation witha consequent maximum improvement in the iiow of oil from the formation.

A special feature of this invention lies in the fact that the combustionof the oil takes place within an envelope of oil which is simultaneouslyheated by .the combustion. In using the submerged heater the heattransfer from the flame to the formation is accomplished by a two-stepprocess which may be arbitrarily designated as" 1) direct, and (2)indirect. The direct heat transfer process takes place where the heat ofthe ame, by virtue of its submergence, is transferred directly to theenveloping oil. In this step there are no hot gas-to-metal ormetal-to-liquid interfaces such as are necessary in the conventionaliiame heaters and accordingly the heater of this invention is notimpaired by gas or liquid films, dirt, scale or other insulatingbarriers which might be deposited upon the burner surfaces. Thus theburner of this invention may be operated during long on-stream periodswith a minimum of vmaintenance being required. Furthermore, theformation of hot spots due to corrosion or plugging within the metaltubes of the conventional heaters. is not a problem.

The heat absorbed Aby the'oil from theA submerged flame' is thentransferred at least in part to the vanes surrounding the heat transfersection such as was shown in Figures l' and 2. The heat transferredthrough such vanes ultimately reaches the formation by radiation orconvection. In this second part of the heat transfer, i. e. through thevanes, the problem of varying oil temperatures is not met and a maximumcontrol of the heat transfer can be had.

The heat transfer unit of the apparatus provided by this inventionpreferably has a converging zone and a diverging zone of the Venturitype. Units of this type are well known and are described, for example,in Principles of Chemical Engineering vby Vilalker., Lewis, McAdamsA andGilliland, i937 edition onpage 68 et seq. Pref- 8 l erably theconverging zone has a total angle of about 25 and the diverging zone hasa total angle of about 7.

The foregoing disclosure of this invention is not to be considered aslimiting since many variations and modifications can be made by thoseskilled in the art without departing from the spirit and scope of thefollowing claims.

I claim:

1. In a method for increasing production from an oil well in which awell tubing communicates from the earth surface to a body of petroleumat the bottom of the well bore, the steps which comprise introducing a,stream of oxygen-containing gas directly into and below the surface ofsaid body of petroleum and igniting the mixture of oxygen-containing gasand petroleum vapor which is thereby formed to produce a flame submergedin said body of petroleum, said stream of oxygen-containing gas beingdirected upwardly within said body of petroleum and towards the openingin said well tubing thereby causing said flameand the combustionproducts thereof to be directed upwardly and towards said opening insaid well tubing.

2. The method of claim 1 wherein the oxygencontaining gas is air.

3. In a method for increasing production from an oil Well in which awell tubing communicates from the earth surface to a body of petroleumat the bottom of the well bore, the steps which comprise introducing astream of oxygen-containing gas directly into and below the surface ofsaid body of petroleum; igniting the mixture of oxygen-containing gasand petroleum vapor which is thereby formed to produce a flame submergedin said body of petroleum, said stream of oxygencontaining gas beingdirected upwardly within said body of petroleum and towards the openingin said well tubing thereby causing said flame and the combustionproducts thereof to be direoted upwardly and towards said opening insaid well tubing and by their jet action to assist in raisingnon-combusted petroleum through said tubing; Awithdrawing saidcombustion products and non-combusted petroleum upwardly through saidtubing, and transferring heat from said combustion products andnon-combusted petroleum to the surrounding formation.

4. The method of claim 3 wherein the oxygencontaining gas is air.

-said body of petroleum.

6. The method of claim 3 wherein a portion of the non-'oombustedpetroleum is returned to the body of petroleuin in the wellboresubsequeni.`

to the transfer of heat therefrom.

7. A well heating apparatus comprising a combustion chamber having afluid outlet in the upper surface thereof and at least one port adaptedto permit the flow of liquid into said chamber when the latter issubmerged in a body of said liquid, gas inlet means positioned withinsaid chamber and directed towards the fluid outlet thereof, ignitionmeans positioned within said chamber adjacent said gas inlet means, andheat transfer means having a uid outlet and a iiuid inlet, said heattransfer means being attached to said combustion chamber in such mannerthat the fluid inlet ofthe heat transfer means is in register with theiiuid outlet of the combustion chamber.

8. A well heating apparatus comprising a cylin drical combustion chamberhaving a closed lower surface, an open upper surface and a lateralsurface provided with at least one port adapted to permit the flow ofliquid into said chamber when the latter is submerged in a body of saidliquid, gas inlet means positioned within said chamber and having a gasoutlet directed towards the opening in the upper surface of saidchamber, ignition means positioned within said chamber adjacent to saidgas outlet, and tubular heat transfer means attached to said combustionchamber having a uid inlet in register with the opening in the uppersurface of said combustion chamber and a fluid outlet adapted to beingjoined to a well tubing.

9. A well heating apparatus according to claim 8 wherein the tubularheat transfer means is of Venturi shape having exterior iins.

10. A well heating apparatus according to claim 8 and comprising meansfor withdrawing from the upper portion of the heat transfer means aportion of the uid passing through said heat transfer means.

References Cited in the le of this patent UNITED STATES PATENTS NumberName Date 1,449,420 Kreager et al Mar. 27, 1923 1,473,348 Howard Nov. 6,1923 1,554,444 Loomis Sept. 22, 1925 2.272,47? Pfleger Feb. 10, 19422,444,754 Steffen July 6, 1948 2,444,755 Steffen July 6, 1948 2,500,990Higginbotham et al. Mar. 21, 1950 2,506,853 Berg et al. May 9, 1950

